Train control



Sept. 13, 1932. c. s. BUSHNELL TRAIN CONTROL 2 Sheets-Sheet 1 Filed Oct. 21. 1922 ATTORNEY Sept. 13, 1932.

c'. s. BUSHNELL. V TRAIN CONTROL Filed 001;. 21, 1922 2 Sheets-Sheet 2 Patented Sept. 13, 1932 is'zasee unite CHARLES S. BUSHNELL, OF1BOGHESTER, NEW YORK, ASSIGNOB TO GENERAL RAILWAY" SIGNAL COMPANY, 015 GATES, NEW YORK, A CORPORATION OF NEW YORK 'rnniiv ooN'rnoL ticularly to a system in which certain speed restrictions are enforced.

According to this invention, itis believed desirable to make the automatic traincontrol system supplement the block signal system and he vigilance and care with which ongineers observe and obey the signal indications with rare exceptions, in order that all of the safety of train movement now attained without train control may beretained, and the automatic train control system reserved to safeguard the train in those exceptional cases where the engineer fails for some reason to perform his duties properly. If the vigilance of the engineer is in some manner maintained, it will be evident that, before an accident can result, not only must the signal system .and the engineer fail, but

also the train control equipment; Whereas if the engineer becomes lax in h s observance of the indi tions of the block signals or care dicated, it becomes necessary to encourage or force the engineer some way to perform his duties. in the usual way in spite of the train control equipment.

in accordance with the theory of main taining vi ilance, above outlined, it is contemplated in this invention to provide a de-' vice, conveniently termed an acknowledging.

in acting upon these indications, the of the train is largely dependentupon ipates such application by taking an appropriate action.

In addition to this acknowledging device, this invention contemplates the provision of automatic mechanism compelling the train upon entering a caution block, or also a danger block, if desired, to reduce its speed to some predetermined minimum or control speed, such as 20 miles per hour. It. is contemplated that this enforced reduction in speed serves to prevent the engineer, careless- 1y or intentionally, running his train through a caution block, after having properly ac-, knowledged the restrictive signal, without reducing speed, perhaps'in hopes that the neirt signal ahead will change to a more favorable. indication by the time the train reaches it. Putting it another way, the purpose of com pellinglreduction in speed in. each caution? block, assuming proper acknowledgment of thesignal has been made, is to obviate the 0bjectionable practice followed by some engi neersin running the caution signal,? that is, running their train through a caution block without full regard to their speed and braking-distance, under the conviction that the signalin advance will have cleared up by the time itis reached.- 7

Generally speaking, the primary objects of the present invention are to devise a simple and efiicient combination or organization of parts and circuits by which the engineer is compelled to acknowledge each restrictive signal indication, and is also required toreduce his speed to some selected control speed. Other specific objects, characteristic features, and advantages of the invention will appear hereinafter as the description progresses.

In describing the invention in detail, reference will be made to the accompanying drawings, in which Figure 1 illustrates in a simplified and diagrammatic manner one form of car apparatus and trackway equipment embodying the invention, the various parts and circuits being shown more with the purpose of facilitating explanation and understanding of the" invention than with the object of showing the precise construction and arrangement pref erably employed in practice;

Fig. 2 is a diagrammatic view, similar to Fig. 1 illustrating a slightly modified arrangement of car equipment; and

Fig. 3 is a fragmentary diagrammatic view showing a still further modified construction of the car apparatus.

Referring first to the embodiment of the invention shown in Fig. 1, and taking up the trackway equipment, the track rails 1 are bonded together in the usual way by bond wires and channel pins, or the like; and these tracl'c rails are divided into blocks of the desired length by insulated joints 2 in conformity with recognized block signal practice, only one block E with the portions of adjacent bloclrs D and F being shown. Since the devices and circuits associated. with these blocks are the same, for convenience they will be given the same reference characters with distinctive exponents. Each block is equipped with a normally closed track circuit of the usual and well-known construction, comprising a track battery 3 and a track relay 4, with the usual adjuncts, such as limiting resistance, battery chutes, relay boxes,

known structure and control circuits, it bei a: understood that these signals will give the usual clear, caution, and stop indications, dependent upon the presence or absence of trains in the corresponding block and in the next block in advance. The adaptability of the train control. system of this invention to block signal systems of other types, employing other types of trackw'ay signals or other forms of control circuits, is considered to be so evident as to require no specific illustration or description. 7

The train control system of this invention in its simplest form,'which has been selected for the purpose of explaining the nature of the invention, requires the communication of a stopping impulse or influence from the trackway to each passing vehicle at each caution signal, with or without a similar stopping impulse at each stop or danger signal; and for this purpose there is located adjacent to the entrance end of each block (traffic being from left to right as indicated by the arrow) a track element or inductor T, which may be" disposed a short distance in the rear of the insulated joints 2 defining the entrance to the block in question, or opposite such joints, or a distance in advance thereof, depending upon the type of control circuits for these track elements. In the particular arrangement of control circuits shown, track element T is located a short distance in the rear of the insulated oints at the entrance of the corresponding block, and the controlling condition of said track element is governed by a line relay 6 that is controlled by the track relays of the corresponding block and the next block in advance, as clearly shown on the drawing. It is noted here that the variouscircuits are shown in a conventional manner with. the reference character B inclicating a connection directly to one terminal of a battery or other source of current and the reference characters C or N indicating a direct connection to the other terminal of the same source, it being understood that several batteries or other sources of the appropriate voltage and current capacity may be used in the respective circuits in conformity with engineering practice.

The track element or inductor T comprises in general a U-shaped core or yoke 7 of soft iron laminations, a coil or winding 8 on said core, together with a suitable support or mounting for housing and protecting said core and coil which may take various forms and which for simplicity is not shown. The yoke 7 is provided with enlarged pole pieces which are disposed a considerable distance above the top of the track rails and outside oneoftherails. In one specific arrangement, the track inductors are located with their pole pieces about 2 above the level of the top of the running rails and with their center lines about 19 outside of one or the other of the running rails. The coil 8 of the track inductor T is connected through a front contact 9 of corresponding line relay 6, and thus is in a closed circuit of preferably low resistance when said line relay is energized.

The locomotive, motor car, or other railway 3 vehicle, equipped with this invention is shown diagrammatically as comprising two pairs of wheels and axles 10 and 11. Carried on this vehicle is a car element or receiver L, which is housed and protected, and suitably supported from the frame or other part of the vehicle in position to pass directly over the track inductors T. The car element L comprises a U- shaped core or yoke 12 of soft iron laminafions, said cores being similar in size to the cores of the track inductors and having simi lar enlarged pole pieces. On one leg of the core 12, preferably the forward or leading leg, is a primary or exciting coil P; and on the other leg is a. secondary or receiving coil S. It is noted here that only one car element L has been shown, permitting the locomotive or other vehicle to travel pilot first in the normal direction of traffic and receive influencesfromthetrack inductors T; and it is to be understood that if it is desired to exert control with the locomotive traveling tender first in the normal direction of traffic, an additional car element and suitable control means is to be employed. This and other ad juncts or adaptations of the specific construction forms no part of this par icular inven tion, and to avoid undue complication in illuc tration and description, these auxiliary features are not shown. I .A'track inductor T in the active stopping condition produces an influence upon the car element L, specifically a change of current in the secondary coil S thereof, as explained more fully hereinafter and a suitableelectroresponsive device, responsive to such current changes in said secondary coil, is provided to translate or convert this induct ve influence or impulse into control for the working parts of the carvequipment. l/Vhilc this electro-re sponsive means, or translating equ pment may take various forms, there is shown an arrangement comprising a main control relay CR, and a. repeater relay RR. These relays are, of course, constructed and have electric characteristics suitable for their respective duties, and also are properlysupported upon the locomotive or other vehicle so asto be immune to shocks, jars, and vibration. The armature of the control relay GR is shown. conventionally and is pivotally supported at the middle and rocked about its pivotal axis by a spring, and in the other direction by n t c attraction if the coils of the relay are sufficiently energized. This armature or con tactfinger 13 cooperates with two stationary and insulated contacts, shown conventionally as arrows, which are normally closed while said relay is effectively energized. The repeater relay ER is provided with a similar armature or contact finger is pivoted. its center and provided with two front contacts and a back contact as shown.

The control impulses or influence com municated from the trackway to the vehicle in accordance with this invention, is utilized in a suitable manner for the regulation of the movement of said vehicle, preferably by operating a suitable brake applying mechanism.

at is contemplated that such brake applying mechanism will act directly upon theairbrake system commonly used, and in some one of the well-known ways, produce an automatic brake application in the proper manner, suitable provisions being made in this mechanism to prevent the engineerfrecharging and releasing, to produce a. limited reduction in brake pipe pressure, and otherwise uponthe air-brake equipmentin accordance with recognized and accepted practice.v The particular character of this brake applying mechanism, however, forms no part of the present invention, and consequently such meci anism or the primary controltherefor, has been illustrated conventionally and desig In conformity with the principle of enforcing vigilance on the part of the engineer, as previously explained, a hold-by or acknowledging devlce or contactor, des1g-.

nated as a whole A, is provided asa part of. the car equipment shown in Flg. 1. This acknowledging contactor Ais shown in a simplified form and comprises a plunger 16, with a suitable knob for facilitating its manual manipulation, which is supported in guides 17, and is pressed upward by a spring 18 between its knob and one of its guides. This plunger 16, when depressed manually in opposition to the spring 18, forces a spring contact linger 19 into engagement with a stationary insulated contact, shown conventionally as an arrow. Atthe same time another rigid contact finger 20 is released and is moved downward by a tension spring 21 a rate determined by a suitable deal-snot or timing mechanism 22. This rigid cor-tact linger 20 is provided with a resilient spri g and stop which cooperateswith stationary contact, (shown as an arrow) in such way that when said finger 20 attains predetermincd lower position, the spring 23 engages the stop and is pulled out of contact with its stationary contact.

. From the foregoing explanation of the diagrammatio showing of the acknowledging contactor A, it. will be observed that this devicev generally speaking, comprises normally open contacts, which are closed when said contactor is manually actuated, and normally closed contacts 23, which are automatically opened if the contactor is held in its actuated position longer than a predetermined time. In connection with this acknowledging contactor A there is preferably employed a suit able signal operable upon the flow of current, this signal being shown conventionally as a bell 24-, which is of the single stroke type or one which does not cause intermittent interruption of its. circuit while operating.

The en ineeris penalized for his failure to talre appropriate action when required by being compelled to operate the reset device, which is preferably located so that it is accessible only from the ground and can not be manipulated until the train has been brought to a stop, or this device is sealed or arranged in some other suitable manner, so that its operation involves considerable annoyance, publicity, subsequent d splacement or similar penalty. It may be saidthat the purpose is to make the operation of the reset device, as compared with the simple manipulation of the acknowledging contactor A, so obj ectionable that the engineer will prefer to work the acknowledging contac'tor rather than be obliged to operate the reset device. This reset device, as shown in the simplified form of the invention, comprises a spring push button or switch blade 25 controllin a normall tual speed. The speed-responsive device or governor G is connected to and driven by a shaft 26, supported in suitable bearings 27 and suitably coupled to one of the axles of the vehicle, as by bevel gears 28. The shaft A? 26 is rotated at a speed proportional to that of the vehicle, and the weights 29 of the speed-responsive devices are thrown outward by centrifugal force against the opposition of a s ring 30 to lower a slidin sleeve or col- .i O D lar 31 to a position corresponding with the instantaneous existant speed of the vehicle. Thus the position of the collar 31 corresponds to the actual speed of the vehicle. This collar 31 is provided with an insulated disk 32 arranged to engage one of a pair of spring contacts 33 and cause separation thereof for speeds in excess of a predetermined maXimum, this maximum speed corresponding to that at which a train may safely run normally under clear si nals, say, 60 miles per hour. The collar 31 also shifts up and down the outer end of an arm 34 fixed to a rocking shaft 35, the connection between the arm 34 and said collar 31 being made in a wellknown manner and so as not to interfere with rotation of said collar. The rocking shaft 35 has arms 3(336 which are pivotally connected to one end of corresponding floating levers 37 and 37 Thus, one end of the floating levers 37-37 are automatically shifted to different positions corresponding to the existing actual speed of the vehicle.

The shaft 26 is coupled by bevel gears 38., with a shaft 39 having a universal connection to an auxiliary shaft 40. Fixed to the auX- iliary shaft 40 is a worm 41 arranged to drop into mesh with a worm gear 42 on a cam shaft 43, said cam shaft being supported in suitable bearings 44. The worm gear 42 has a cutaway portion in its periphery as shown. The auxiliary shaft 40 tends to drop by its own weight to bring the worm 41 into mesh with the worm gear 42 and is held in its raised position by a cam starter magnet or solenoid US, the core or armature- 45 of which has a pivotal connection to a sliding sleeve 46 loosely mounted on said shaft 40. The upward and downward movement of the shaft 40, throwing the worm 41 out of and into engagement with the worm gear 42, is used to open and close certain contacts; and in the simplified arrangement shown, a reciprocable bar 47, having sliding and rotary connection with the shaft 40, and supported by fixed guides 48, shifts spring fingers 49, 50 and 51 by insulated pins. l i ith the shaft 40 raised as shown, the spring fingers 50 and 51 are forced into engagement with cooperating contacts shown conventionally as arrows, while the finger 49, is forced out of engagement with its cooperating contact.

When the shaft 40 drops, fingers 50 and 51 are shifted to break contact, and finger 49 is shifted to make contact.

The cam shaft 43 has fixed thereto two permissive speed cams 52 and 53, one 52 for controlling the brakes, and the other 53 for controlling a suitable preliminary warning signal. These cams 52, while shown in a simple form, are in practice carefully shaped with due regard to the travel of the collar 31 of the speed-responsive device G and the relative movements of the other parts of the apparatus, so as to prescribe a variable limiting or permissivespeed for the train at all points in its travel, as said cams are turned, corresponding to a predetermined speed-distance curve. These permissive speed-distance curves are in practice based upon the braking performance of the train in ques tion; and generally speaking, these curves will show the different speeds at the different points in the block at which the train may be traveling and yet be brought to a stop by an automatic brake application before reaching the end of the block. The precise shape of these permissive speed curves, however, is subject to considerable variation according to the requirements of the railroads, and curves may be based upon braking performance on the level grade or a down grade or a given weight of train. Irrespective of the detail factors determining the shape of the cam, it will be readily understood that this cam is intended to set up a gradually reducing speed limit as the train progresses after the cam movement is started, so that the train is compelled to maintain its speed below a gradually reducing limit, otherwise an automatic brake application occurs. The 1'.

cams 52 and 53 although preferablv based upon the same factors, are slightly different in shape, so that a warning signal controlled by cam 53 will be given a short interval of time before the brakes are automatically applied by the action of the other cam 52, thereby providing a preliminary warning signal to advise the engineer that his speed is approaching the limit at which a brake application will occur.

The floating levers 37-37 carry at their ends freely revoluble rollers 54 and 54 which bear upon the edges of the respective cams 52 and 58. Contact operating members -55 are 'pivotally connected at intermediate points of the floatinglevers 37-37 and when these intermediate points ha; been raised to a predetermined extent, insulated striking pieces on said members 55-55 engage contact springs of a pair of contacts 56 56 respectively, thereby inter rupting circuits therethrough.' Springs 5 and 57 connected to the contact operating members3737 ,serve to maintain the rollers 54-54 in contact with the cams.

The cams 52 and 53 are shown in their maximum speed positions, and it will be noted that the radii of these cams increase as they are turned in either direction from the normal or initial position shown. This increase in radius forces upthe rollers 54-54 raising'the corresponding ends of the floating levers 37-37 and it will be evident that unless the other ends of said i floating levers are sufficiently low, that is, the 7 actual speed is sufliciently low, the contacts 56 and 56 will be opened. It may be added that this particular construction shown and permitting control of circuits, dependent upon the position of a part accordance with the actual. speed and another part changeable in accordance with the de sired permissive speed, is diagrammatic and urged to the normal or initial. position shown by a spring 58 anchored at one end to a stationary' part, and coupled crank arm 59 fixed on said shaft. On the cam shaft 43 is fastened an arm 60 which is arranged to engage one or the other of two contact springs 61, 61 depending upon the direction of rotation of the cam shaft,

The cam shaft 43 is biased or after said cam shaft has attained its minimum speed position; and when the spring 61 or 61 is thus engaged by the arm 60, it

is shifted into contactwith a suitable fixed contact, shownconventionally as an arrow.. 'If the closure of'circults in'thls way fa ls to cause restoration of the cam shaft by the action of the spring 58 to its normal or ini-' tial position, as hereinafter described, the cam shaft will be rotated a, short distance further untilthe worm 41 engages-the cutthe worm gear.

away or mutilated portion in 42, whereupon further movement of the cam snaft ceases.

The maximum speed prescribed by the cam 52 in its normal or initial condition is preferably the same or slightly higher than the speed at which the contacts 33 are opened directly by the movement of the collar 31 of the speed-responsive device G. Theradius of the warning signal cam 53 when in its normal changeable in is intended to at the other end to a condition, is selected so as to cause operation of contacts 56 and the giving of the warning slgnal at a speed somewhat less than the maximum speed at which the contacts 33 open, say i 7 preferably corresponds to some moderate control speed,'such as 20 or 25 miles per hour, this minimum or control speed being such that the engineer may release the brakes and proceed after coming down to such speed without having to stop. In this connection it is obvious that the speed limits above men tioned should be different for freight trains than for passenger trains, because freight trains have different normalrunning speeds and also can not release the brakes without stopping at as low a speed as a passenger train.

The warning signal above mentioned is shown diagrammatically as a whistle W, operated by compressed air or the like whenever its controlling solenoid is deenergized. The circuit for normally energizing the control magnet of this whistle W merely includes a suitable source of energy as a battery and the contact 56 and may be readily traced on the drawings.

0pemtion.-In describing the operation in its various steps, it is expedient to consider first the normalcondition or position of the various parts of'the car apparatus, including the various circuits controlling these parts, and then take up the action of these parts under difieren't conditions. cuits of the car apparatus shown in Fig. 1, are in the normal position corresponding to the movement of the train under clear signals;

The main control relay OR is normally maintain-ed energiz'ed'by a circuit which may. be traced as follows :-commencing at B, contact finger 13, front contact, wires62 and 63,

relay CR, wires 64 and 65, contact 51, wires 66 and 67, secondary coil S, to C, it being.re-

membered that the'letters'B and G indicate connections to the opposite terminals of a suitable battery or other source of energy.

The repeater relay BB is maintainedenergized so long as the control relay OR is energized by a circuit through a front contact of said control relay and wire 68, as readily traced on the drawings.

Parts and cirios follows :commencing at 13, wire 69, front contact of relay RR, wire 7 4, reset switch 25, wire 75, maximum speed contact 33, wire 76, finger 20 of acknowledging contactor A and its spring 23, wire 77, device K, wire 7 8, and

primary coil P to C.

- From the circuit just traced it will be noted that the train control device K is connected in series with the primary coil P, so that if the energizing circuit for said primary coil should become interrupted, or the current flow decreases below a safe value, the train control device K will cease to be effectively energized and will operate to apply the brakes and stop the train on the side of safety.

With the parts in the normal position shown, there is established a continuing maximum speed limit which the tain care not exceed without an automatic brake application. If the train exceeds this maximum speed limit, contacts 83 are opened, breaking the energizing circuit of the device K ap plying the brakes. The contacts 56 associated with the cam 52 may be opened at the same time, assuming that the speed limit for the initial position of the cam 52 corresponds to the speed limit at which contacts 38 open, but the opening of contacts 56 at this time produces no effect since these contacts are shunted by Wires 65, 66 and contact 51. The contacts 56 associated with the warning signal cam 53, however, will open before contacts 33 open and apply the brakes, so that the engineer has an advance warning of a brake application due to excessive normal running speed. Incase the normal running maxi mum speed limit is exceeded, as soon as the speed'has been reduced below this limit by the automatic brake application, or by a manual brake application, as thecase may be, the contacts 33 operated by the spoon-responsive device G directly reclose, thereby reenen 'izii the device K and permitting the blftlaGS L0 be released and the train to proceer. other words, there is no particular penalty imposed for exceeding the maximum normal running speed, that is, the train may proceed at once after the automatic slowing ClOWIl thereof without being required to stop For the first condition to be considered, assume that the train passes a caution signal, that the engineerehas been vi ilant and has observed this caution signal, and thatrin recognition of this caution signal he has operated his acknowledging contactor A. The

track inductor T at the caution signal will have its coil 8 open-circuited, so that the core 7 of said track inductor presents ineffect a magnetic loopor partial circuit for the core 12 of the car element. The primary coil P of the car element is constantly energized, as above explained, and tends to send fiux through the core 12; and as this core passes over the core 7, the reluctance of the c circuit through the primary and secondary coils P and S is first decreased from normal to a minimum and then increased from a minimum back to normal. By reason of such change in the reluctance, perhaps aided by diversion of flux from leakage paths around the primary coil P, there is a quick change of flux through the secondary coil S, first an increase and then a decrease. This quick change of flux induces a voltage in the secondary coil S which produces a single cycle of alternating current; and either the first or the second wave of this induced cycle of voltage, depending upon the connections, opposes the battery or other source supplying energy to the main control relay CR, thereby'reducing the current in the coils of this relay to the point where its armature is retracted by the spring. The connections are preferably made so that the relay operates in response to the first half cycle of induced voltage. 7 Thus, as the train passes an active track inductor T, the relay OR is momentarily deenergized, and being a stick relay holds its contacts open until otherwise energized, and since the repeater relay RE is controlled directly by relay OR, the repeater relay RR likewise opens its front contacts and closes its back contact.

The opening of the front contact of the repeater relay RR deenergizes the cam starter magnet OS, allowing shaft 40 to drop and bring worm 41 into mesh with worm gear 12, thereby commencing the gradual rotation of the cam shaft. At the same time contact-s 50 are opened, so that reclosure of the front contacts of repeater relay RR does not cause energization of the cam starter magnet CS,which must be restored by another circuit, as hereinafter explained. In short, the cam is started into operation upon passage over the active track inductor T, and irrespective of the condition of the relays CR and RR, continues in force until restored.

Assume now that the engineer was alert and observed the caution indication of the signal prior to the passage of the vehicle by the active track element, and that the engineer, before deenergization of the relays GR andRR, pressed down the plunger 16 of the acknowledging contactor A. Under these conditions, while the opening of the front contact of relay Rilbreaks the normal energizing circuit for the device K previously traced, the closure of the open contacts 19 of the acknowledging contactor A establishes circuit for holding the device K energized.

in spite of the dropping of relay RR. Th s auxiliary holding circuit for the device K may be traced as follows :commencing at battery 13, wire 80, contacts 15 of device K, wire 81, contacts 19 of acknowledging contactor A, vwire 82, bell 24, wire 83, reset s itch 25, wire'75, contacts 33,'wire 7 6, normally closed contacts of acknowledging contactor, wire 77, wire 78, primary coil P to C.

Also, closure of the contacts 19 of the acknowledging contactor A permits re-energization of the main control relay GR, provided the she has dropped to startthe cam as intended' Thispick-up circuit for the relay CR may be traced as follows zcommencing at B, wire 80, contact 15 of device K, wire 81, contacts 19 now closed, wire 82, bell 24, wire 83, wire 7 1, back contact of relay RR, wire 84, contact 49 now closing by dropping of shaft 40, wires 85 and 63, relay CR, wire 64, contacts 56, wire 67, secondary coil S to C.

As soon as relay OR is reenergized to close its front contacts, relay BB is likewise reenergized, thereby establishing the normally closed energizing circuitfor the device K, so that the contacts 19 may now be opened without the application of the brakes.

From the foregoing it will be noted that the engineer, by making timely operation of the acknowledging oontactor accomplishes two things, first, avoids the deenergization of the device K and the resultant brake application that would otherwise occur upon dropping of the relays CR and RE, and second, restores the relays CR and RR. It will also be noted that these functions can only be performed so long as the contacts-15 of the device K are closed, that is, before the device K has operated.v Consequently, the operation,

of the acknowledging contactor A must be made prior to the passage over the active track element, and can not be made later. In short, the engineer, must watch out for the signals, and can not wait until, by the application of the brakes or otherwise, he is advised that a caution control has been received. The hell 2% is sounded when the front contacts 14 of the relay RR open, that is, providing the contacts 19 have been closed the engineer, said bell being shunted by wire 7 4:

' and th front contacts 1% of relay RR so long as contacts 19 are closed, and does not sound until said front contacts 14 open. In other words, after the contacts 19 have been closed dging By reason of the much greater resistance of the bell 2 as compared with he verylow resistance of the wire 7% and the front contact l l of the relay RR, practically no current flows through the bell 24 under these conditions; but as soon as the front contact 14 of the relay RR opens, the bell 24 is conin s with the device z i the primary coil P and is supplied with enough. current to cause it to sound. The

bell 24 serves'to inform the engineer that he has passed the track inductor and may shortly release the acknowledging contactor. The sounding .of this bell 24 also informs the engineer that the system iswo-rkingproperly.

In orderv to prevent the engineer from defeating the purposes of the system by fasteningdown the acknowledging contactor A, the time control contacts 23 are provided, so that, if the plunger 16 is held down too long, the energizing circuit for the device K is directly opened and the brakes applied. The adjustment of the dash-pot or timing device 22 is such that the time for opening of the contacts is long enough to give the engineer reasonable latitude in passing'an active inductor, but too short to permit him to pass two signals in succession by the same manipulation.

Assume now that the engineer is asleep,incapacitated, or for some other reason fails to observe or correctly interpret the cantion signal indication and consequently does not make a timely operation of the acknowledg contactor. Under these conditions, when the relays CR and RR assume the ole-energized pos ion, the normally closed energizing circuit for the device K is broken and there being no auxiliary maintaining circuit, said device at once operates and applies the brakes. Upon such operation the contacts 15 open thereby preventing restoration of the rela CR mani ulation of the acknowled 1 ing cont-actor A. Incidentally, the cam star"- er magnet is deenergized and the cam is s rted in operation in the same manner as it the engineer had properly acknowledged the signal; but the brakes are applied and the train is immediately brought to a stop. Before the device K can be recnergized and the brakes released, the reset switch 25 must be actuated; and since the operation of this switch is attended with a penalty, as previously explained, it is clear that the engineer would much prefer to watch out for the signals and operate his acknowledging contactor, Operation of the reset switch 25 supplies current from the "battery to the wire Hand through the back contact of relay R picks up relay CR, and consequently relay RR. When the reset switchis released and allowed to return to'the normal position shown, then the train control device 1s recnergized and the train may proceed, subject, however, to,

lil

the engineer does not himself regulate the speed of his train properly, guided by the warning signal, and allows the speed at any time to exceed the permissive speed, contacts 56 open and break the energizing circuit for therelay CR, which in turn deenergizes relay RR and applies the brakes. The engineer must then stop the train and operate the reset switch 25.

If the acknowledging contactor is operated at the time contacts 56 open, the device K may be maintained energized, as previously explained, but the relay CR can not be picked up since its circuit broken at contacts 56; and unless the speed is quickly reduced to reclose contacts 56, the contacts 23 of the contactor A will open and apply the brakes.

If, however, the engineer properly controls the speed of his train, the cam shaft is turned after a predetermined distance in travel to the point where the arm 60 thereon closes contacts 61 or 61 whereupon the cam starter magnet CS is reenergized by a circuit as fol lows, it being remembered that relays CR and RR must he picked up at this time battery, wire 69, front contacts of relay RR, wire 70, wire 86, contact 61 or 61 wires 87 and 73, cam starter magnet CS to Q. As soon as the cam starter magnet CS is energized, it lifts the shaft 4-0, closing contact 50, so that said magnet is maintained energizcd by its stick circuit, independently of contacts 61 or 61 As soon as worm tl is thrown out of mesh with worm gear 42, the cam shaft isv restored to its normal or initial position by the spring 58. The train may now run at any speed below the maximum prescribed by contacts 33 until the cam is started into operation again.

Fig. 2 illustrates a slight modification of the invention, employing the same apparatus and devices shown in Fig. l, but using a different form of control for starting the cam shaft. Since most of the devices and circuits are the same and have the same functions as those already described in connection with Fi 1, these parts and electrical Connections have been given the same reference characters, allowing the description of Fig.1 to be used also for Fig. 2 in most respects.

In the modified arrangement of Fig. 2, the cam starter magnet CS is controlled by the acknowledging device A, and by the contacts 15 of the brake setting device, so that whenever said acknowledging contactor is actuated, or the brake setting device K is set into operation, the cam starter magnet CS is deenergized. The cam starter n agnet 055 has a stick circuit through contacts 50, and pick up circuit through contacts 61-61 Another difference is that Contact 51 shown in Fig. 1, instead of being opened when the shaft 40 drops, is opened when the cam shaft 48 has slightly turned from its initial position. Another difference is that the contact 49 included in the pickup circuit for the relay CE is omitted, and said relay is picked up at once when tie acknowledging contactor is actuated, whether the cam starter is deenergized or not.

The operation of the modification of Fig. 2 is substantially the same as that of Fig. l and need not be described in detail. The engineer must actuate the acknowledging contactor A. at each active track inductor in or to avoid deenergization of the brake setting device K. 1f the control relay CE in releasing once causes deenergization of the brake setting device K and opening of its contacts 15, the brakes are held applied until the parts are reset by manipulation of reset switch 25. Unless, therefore, the engineer acknmvledges at each caution signal or cor responding control point, the brakes are ap' plied and the apparatus must be reset from the ground. Whenever the acknowledging contactor is actuated, the cam starter magnet CS is deenergized and can not be reenergized until the cam has run down to its minimum speed position closing contacts 61 or 61 The important distinction between the dis closures of Figs. 1 and 2, is that the cam is started by the releasing of the relays by the reception of an influence from the trackwa-y in Fig. l, but is started by the act of acknowledging in the arrangement of Fig. 2. The

purpose of arranging it so that every operation of the acknowledging cevice starts the cam is to make it more sure that the cam will always be started at each caution signal. To illustrate, it may happen that the proper influence may not be received at the entrance to some particular caution block, for some reason or another; but the engineer, not knowing this, will operate his acknowledging contactor in the usual way, so that the cam will be started in operation and the desired speed limits imposed in spite of the fact that the control influence was not received. In other words, the vigilance and care with which engineers almost without exception will, it is believed, observe restrictive signal indica-,

tions and operate the acknowledging contactors, acts as a check upon the proper performance of the automatic influence communicating equipment, so that there must be a failure on the part of the engineer as well as the failure to receive an influence from the trackway before there can be a failure to start the cam.

Another embodiment of the invention, employing similar principles and functions hereinafter explained, is shown in Fig. 3. In this modified arrangement, generally speaking, the brakes are applied as the train passes each caution signal or corresponding control point, but if the engineer has properly acknowledged the signal, the brakes may be released after the train has reached a predetermined speed. Incidentally, if the train should happen to be traveling at a speed lower than this predetermined control speed at the time it passes the caution signal, no automatic brake application will occur'pro vided the engineer properly acknowledges the signal. v

The modification of Fig. 3 employs many of the devices hereinbefore described and for convenience corresponding parts have been given the same reference characters. The influence communicating means is the same, including the main control relay CR and the repeater relay RE. The acknowledging contactor A is the same, with its normally open contact 19 and its normally closed time controlled contact 23. The reset switch R performs the same function as previously described, but on account of the difference in the circuit arrangement, the normally closed contact of the switch is provided with two separate switch blades or contacts and 25 The brake setting or train control device K is the same and is provided with the same normally closed contact 15. The speed-responsive device or governor G has the insulated collar 32 which opens contacts 90 unless the speed of the train is belowsome moderate control speed, such as 20 miles per'hour.

iQpemtion of Fig. 5.Normally, that is, when the train is traveling under clear trafiic conditions, the main'control relay is maintained energized by a stick circuit through its front contact and the secondary coil S as will be readily traced on the drawings. The

repeater relay BB is maintained energized by a stick circuit :-commencing' at B, front contact 18 of relay GR, wires 91 and 92, front contact 93 of relay RR, wires 94 and 95, re-

lay RR, and wire 96 to C. The brake setting or train control device is maintained energized normally by a circuit as follows :-commencing at B, wire 97 front contact 98 of relay RR, wire 99, normally closed contacts 23 of acknowledging contactor A, wire 100, closed contact 25 of reset switch R, wire 101, device K, wire 102, through the primary coil to C. 1

When the train passes an active track inductor, the relay CR is momentarily deenergized as previously explained. Assume for the first condition that the engineer properly acknowledges the signal by actuating the acknowledging contactor A, and that the speed of the train is above the control speed at which contacts 90 open. The releasing of the relay CR breaks the stick circuit for the relay RR, and contacts 90 being open, relay BR remains deenergized. The opening of the front contact 98 of relay BB breaks the energizing circuit for the device K, applying the brakes. In this connection, it should be noted that the speedcontacts 90 when closed, form a shunt for the stick contacts 93, so that the relay RR functions as an ordinary nonstick relay when the speed of the train is below the control speed limit but functions as astick relay when the speed is above this value. This deenergization of the device K, however, is briefly retarded by the fact that when contact'finger 98 drops and makes its back contact a deenergized closed circuit including the device K and primary coil P is formed; and in accordance with well-known principles of self induction, and the dissipation of the energy stored in a magnetic field linked with a closed circuit, the current in this circuit dies down gradually. -When the engineer depresses the acknowledging contactor A, a pick-up circuit for restoring the relay OR is formed as follows :commencing at battery B, back contact 103 of'relay RR, wire 104, contacts 15 of device K, wire 105, contacts 19 of acknowledging contactor A, wires 106,107 and 108 to relay CR, and thence through the secondary coil to C. The operation of the device K is delayed in the manner above described long enough to permit relay CR, which is quick-acting, to pick up after dropping of relay RR before contacts 15 open. The relay GR once picked up is held up through its normal stick circuit. After the train has been brought down to the con trol speed by the action of its brakes and contacts 90 close, relay RE is picked up, since relay CR has been restored, and'the contacts 90 establish a shunt for the stick contacts of relay RR, as can be readily seen on the drawings. Consequently, with relay RR again picked up, the device K is energized, and the brakes may be released. i Since the relay isheld up through its stick circuit independently of the opening of contacts 90, a train thereafter may travel at any speed until it receives another-impulse from the trackway but it'has been assured that the train has been brought down to the control speed inthe caution block-and has not maintained an excessive speed.

For the next case, assume that the engineer properly acknowledges the caution signal, and

that the speed of the train at that time is below the control speed at which contacts 90 may-be open. Under these conditions, the relay GR is restored as before, relay HR is immediately picked up and the device K is only momentarily deenergized if at all.

For the next condition, assume that the en'- gineer is asleep orfor' some other reason fails to acknowledge the signal. Under these conditions, when relays OR and RR drop, and the device K operates, contacts 15 of the device K opening after a short time, so that the only way in which the relay CR can be restored and the brakes released is by operation of the reset device B. The reset device R can not be fastened down, because until it is restored, the device K cannot be energized. Consequently, if the engineer fails to acknowledge the signal, not only are the brakes applied, but also the brakes can not be released until the apparatus is resetlrom the ground; whereas, as previously explained, if the engineer properly acknowledges the signal, he may release the brakes as soon as the speed has been reduced to the predetermined control speed.

In the various modifications above described, no impulse is received at a clear signal, because at that time the coil 8 on the track inductor is included in a closed circuit of low resistance, and serves to choke back or oppose the passage of flux through the core of said track element, thereby preventing a quick change in flux which acts under caution conditions to operate the relay CR.

While difi'ere-nt specific en'ibodiments of the invention have been disclosed, it will be readily recognized that the invention is not limited to these precise forms, but is susceptible of considerable modification and adaptation in practice. Also, it should be understood that in the interests of simplification various expedients that may be employed advantageously in practice to make a complete system of train control have not been shown or described. I desire to have it understood, therefore, that the invention is not limited to the particular arrangements and construction 0]": devices and circuits shown in the drawings.

What I claim is 1. In a train control system for railroads equipped with a block signal system, the combination with trackway means eifective near the entrance to each block to communicate a stopping influence if the corresponding signal indicates caution, of car-carried apparatus responding to said stopping influence and acting to apply the brakes of the car, said apparatus including means permitting release of the brakes after the speed of the car has been reduced to a predetermined control speed provided the engineer has taken appropriate action just prior to and only just prior to the reception of said stopping influence.

2. In a train control system for railroads equipped with a block signal system, the combination with trackway means effective near the entrance to each block to communicate a stopping influence if the corresponding signal indicates caution, of car-carried apparatus, comprising, brake applying means adapted whenever operated to continue in operation until restored, a manually operable reset device accessible only from the ground for restoring said means, and other means rendered elfective by a manual operation thereof by the engineer just prior to and only just prior to the initiation of operation of the brake applying means for restoring that means after the speed of the car has been re duced to a predetermined low speed.

. 3. In a train control system for railroads equipped with a block signal system, the combination with trackway means effective near the entrance to each block to communieats a stopping influence if the corresponding signal indicates caution, of car-carried ap paratus comprising, a stick relay respondingto said stopping influence, an electromagnetic device having a circuit governed by said relay; brake applying means controlled by the electro-magnetic device, manually operable means effective only it actuated prior to the operation or" the brake applying means for restoring said stick relay, and means including a speed-responsive device driven from the wheels of the car for controlling the restoration of said electro-magnetic dcvice.

4;. In a train control system for railroads equipped with a block si 'nal system, the combination with trackWay means efiective near the entrance to each block to communicate a stopping influence if the corresponding signal indicates caution, of car apparatus comprising, brake control means responding to said influence and operable to enforce reduction in speed of the car to a predetermined control speed, and manually operable means effective only if actuated just prior to and only justprior to the initiation of operation of the brake control means for permitting restoration of said brake control means after the predetermined control speed limit has been reached.

5. In a train control system, brake control apparatus including influence elements partly'on the car and partly on the track, a stick device adapted to be deenergized by said influence elements at each caution s 'nal,

and brake setting means eventually actuated by said stick device if said device continues to assume its deenergized position, said stick device when set into operation continuing in operation until restored, and means including an acknowledging device operable manually by the engineer and effective only if actuated prior to the initiation of operation of the brake setting means for restoring said stick device provided the speed of the caris below a predetermined low speed and said acknowledging device is in its effective condition. a

6. In a train control system, a brake setting .appliance on the car which when once initiated continues in operation until restored, a stick relay on the car adapted when deenergized to initiate operation of said appliance, means partly on the car and partly on the track for temporarily deenergizing said relay under dangerous trafiie conditions, manually operable-means effective only if actuated prior to the initiation of operation of the brake setting appliance for restoring said stick relay, and automatic means for restoring the brake setting appliance to normal after the speed of the car has been reduced to a predetermined low speed and provided the. stick relay has been restored.

7. A train control system for railroads eration of the brake setting equipped with a block signal system, trackway means effecting the communication of a stopping influence to the car near the entrance to each caution block, a normally energized stick relay on the car deencrgizcd by such stopping influence, brake setting means including an electro magnet having a stick circuit and controlled by said stick relay, means for restoring said magnet only if the relay is energized after the speed of the car has been reduced to a predetermined low speed, an acknowledging device effective only ii actuated by the engineer prior to the opmeans for reenergizing the stick relay, and manually operable means accessible only from the ground for independently reenergizing the stick relay.

8. Ina train control system for railroads equipped with an automatic block signal, system, the combination with traflic controlled trackway means,

trackway means and having its operation initiated at each caution signal, and acknowledging device on the vehicle operable manually by the engineer and which if operated just prior to the passage of the vehicle by a caution signal prevents actuation of said brake control apparatus, said acknowledging device if left in its operated position for more than a predetermined time, actuating said brake control apparatus, means for restoring said apparatus after the vehicle has been brought to a stop which if left in its active position renders said brake control apparatus active, and other restoring means for said apparatus'eiiective only if the speed of the car has been reduced to a predetermined low speed and the engineer has 0perated the acknowledging device prior to the operation of the brake control apparatus.

9. Car apparatus for train control systems comprising, brake setting means including an electro-pneumatic-valve, trolling said valve, an acknowledging device manually operable by the engineer and effective only if actuated prior to the operation of said valve, and means for re-enervizing the stick relay after the speed of the b car has been reduced to a predetermlned minimum provided said acknowledging device is then effective.

10. A system for automatically controlling the movement of railway trains comprising, brake setting apparatus on a vehicle automatically operated at each caution signal, a speedresponsive device driven from the wheels of the vehicle, contacts closed by the speed-responsive device if the speed is below a predetermined minimum, a circuit adapted when closed to cause restoration of said brake setting apparatus, said circuit including said contacts of the speed-responsive device, and manually operable means on the vehicle effecof brake control 1' apparatus on a vehicle governed by said' a stick relay contive if actuated prior 'to operation of the brake setting apparatus to determine closure of said restoring circuit at another point, said manually operablemeans being so constructed thatit cannot be permanently held in its active condition without eiiecting an automatic brake application.

11. Car apparatus for; train control systems comprising, a brake setting appliance, a manually operable acknowledging 7 device acting if maintained in its operated condition longer than a certain time to cause operation of said'appliance, a circuit acting if. energized to permit automatic restoration of said appliance, means preventing re-energ ization of said circuit until the speed of the car has been reduced to a predetermined low speed, means interrupting said circuit upon opera tion of said apparatus, and means for closing said circuit atone point'upon-operation of the acknowledging device. i i

12. A train control system characterized by the automatic initiation of the operation of brake control apparatus at each caution signal, and the provision of means permitting the' release of the brakes provided the speed of the car is reduced to a predetermined minimum and provided amanual operation is made by the engineer prior to the initiation of the operation of the brake control ap-,

paratus, said last mentioned means including a manually operable acknowledging device which is normally in an inactive; position and which is held in its active position for more than a predetermined period of; time eiiects an automatic brake application.

13. Car-carried apparatus for automatic train control systems comprising, a permissive speed device normally in a maximum permissive speed condition which if initiated gradually restricts the speed of the train in accordance w1th the progress of the train, a normally energized stick device which if energized maintains said permissive speed device in its normal condition, deenergizing said stick device governed by control influences transmitted from the trackway, and manually operable means which if operated prior to the deenergization of said stick device closes a contact in said pick up circuit for said stick device at one point, and other means for closing said pick up circuit at another point.

14. In a system of train control of the character described, the combination of brake setting apparatus set into operation under dangerous traflic conditions and continuing in operation until restored, and means for determining restoration of said apparatus comprising, a speed-responsive device driven from the wheels of the car, and a manually operable acknowledging device effective only if actuatedless than a predetermined period of time prior to and during the time of initiation of operation of said apparatus.

means for 15. Car-carried apparatus for automatic train control system comprising, a stick re 'lay having a stick circuit including a front contact of said relay, influence communicating means partly on the vehicle and partly along the trackway for deencrgizing said stick relay under dangerous traflic conditions ahead, a stick electro-responsive device having a stick circuit including front contacts of said relay and said device, a normally en'- ergized brake setting device governed by said stick device Which'if deenergized applies the brakes of the train, manually 0perable means Which if operated While said brake setting device is in its inactive c0nditions re-energizes said stick relay, and means for picking up said stick electro-responsive device effective if the speed of the train is below a predetermined value and said stick relay is in the energized position.

16. Car-carried apparatus for automatic train control systems comprising, a stick relay having a stick circuit including a front Contact of said relay, influence communicating means partly on the vehicle and partly along the trackWay for deenergizing said stick relay under dangerous traflic conditions ahead, a stick electro-responsive device havingv a stick circuit including front contacts of said relay and said device, a normally cuergized brake setting device governed by said stick device which if deenergized effects an application of the brakes, manually operable means which if operated While said brake setting device is in its inactive condition reenergizes said stick relay, means for c1osing a pick up circuit for said stick electroresponsive device effective if the speed of the train is less than a predetermined minimum and said stick relay is energized, and manual- 1y operable means only accessible from the ground for restoring said stick device to normal.

In testimony whereof I hereby afiix my signature.

CHARLES S. BUSHNELL. 

